Hemodialysis is used for removing toxic wastes from the human body in cases of renal failure. The patient's blood is temporarily brought outside of the body via tubes and passed through at least one semi-permeable membrane, which may be a group of hollow fibers, in a dialyzer. The semi-permeable membrane separates the blood from a dialysate solution. Impurities from the blood pass through the membrane and into the dialysate solutions, primarily by osmotic pressure. The cleansed blood is then returned to the body.
Standard dialysis treatment, using an installed apparatus in hospitals, comprises two phases, namely, (a) dialysis, in which toxic substances and scoriae (normally small molecules) pass through the semi-permeable membrane from the blood to the dialysis liquid, and (b) ultrafiltration, in which a pressure difference between the blood circuit and the dialysate circuit, more precisely a reduced pressure in the latter circuit, causes the blood content of water to be reduced by a predetermined amount.
Dialysis procedures using standard equipment tend to be cumbersome as well as costly, besides requiring the patient to be bound to a dialysis center for long durations. Portable dialysis systems have been developed. U.S. Pat. No. 4,083,777 discloses a hemodialysis system with dialyzer means through which waste impurity-containing blood and a dialysate solution are passed in indirect mass transfer dialyzing relationship for transfer of the waste impurities from the blood to the dialysate solution. The apparatus includes means for transferring waste impurity-containing blood from a patient to said dialyzer means including a flexible resilient tubing pumping section through which blood is pumped and means for returning waste impurity depleted blood to the patient forming a blood flow circuit. Peristaltic pump means are provided with a rotatable pump head assembly including a base member positioned for rotation about a fixed axis with a plurality of circumferentially spaced apart rollers mounted thereon for independent rotation about respective axes parallel to the base member fixed axis.
U.S. Pat. No. 4,443,333 discloses a portable system for dialyzing blood wherein blood passes through an exchange station with the blood contacting one side of a semipermeable membrane and dialysate contacting the other side of the semipermeable membrane, the system comprising elastic tube means adapted to be connected to a blood source and to return blood thereto for conducting blood past a plurality of stations, a blood clot detector and an air bubble detector in communication with said blood tube means, elastic tube means adapted to be connected to a source of dialysate for conducting dialysate past a plurality of stations, means for measuring and regulating dialysate flow, pressure, temperature and conductivity, means for maintaining the dialysate at a lower pressure than the blood during passage through the exchange station, a single motor means having the output shaft thereof connected to at least two peristaltic pumps one for transporting blood in the elastic blood means and the other for transporting dialysate in the elastic dialysate tube means, mechanism associated with the motor means and the peristaltic pumps for maintaining the dialysate flow at about three times the blood flow, each of the peristaltic pumps having an inner arcuate surface, the blood pump having at least one roller associated with the inner arcuate bearing surface to trap the blood tube means therebetween, the dialysate pump having a single roller associated with said inner arcuate bearing surface to trap said dialysate tube means therebetween, actuation of the peristaltic blood pump causing smooth laminar flow of blood in the blood tube means due to the roller, actuation of the peristaltic dialysate pump causing dialysate flow due to a vacuum generated by the single roller resulting in the deformation and return of the elastic dialysate tube means, and control mechanism operatively connected to the blood leak detector and the air bubble detector and to the motor means and to the dialysate flow, pressure, temperature and conductivity measuring means for selectively stopping the dialysate roller thereby halting movement of dialysate through the dialysate tube means and through the exchange station in response to pressure or temperature or conductivity measurements outside of a preselected range while maintaining blood flow and for simultaneously stopping all the rollers in response to a signal from either the blood leak detector or the air bubble detector to shut down the entire system and halt pumping.
U.S. Pat. No. 6,168,578 discloses a portable kidney dialysis system that includes a belt with a drain bag mounted thereon. A pump is also mounted on the belt and coupled between a user and the drain bag. The pump is adapted to pump fluid from the user to the drain bag upon the receipt of a drain signal. Further provided is a pressure switch for detecting when the drain bag is full. A control mechanism serves for transmitting the drain signal to the pump only when the means fails to detect that the drain bag is full. A portable dialysis system called System One made by NxStage is another example of a conventional portable hemodialysis system.
The aforementioned portable dialysis systems suffer from certain disadvantages. First, they are not sufficiently modular, thereby preventing the easy setup, movement, shipping, and maintenance of the systems. Second, the systems are not simplified enough for reliable, accurate use by a patient. The systems' interfaces and methods of using disposable components are subject to misuse and/or errors in usage by patients. For a portable dialysis system to be truly effective, it should be easily and readily used by individuals who are not health-care professionals, with disposable input and data input sufficiently constrained to prevent inaccurate use.
It is therefore desirable to have a portable dialysis system that has a structural design configured to optimize the modularity of the system, thereby enabling the easy setup, movement, shipping, and maintenance of the system. It is further desirable to have system interfaces, through which patients input data or deploy disposable components, configured to prevent errors in usage and sufficiently constrained to prevent inaccurate use.